This invention relates to bead process control. More specifically, this invention relates to a method and system for bead process control using a profiler.
When performing an automated welding process it is important to maintain certain bead dimensions within specified ranges in order to achieve the proper weld strength. Variations in weld bead geometry can result from uncertainties in the wire feed rate, varying surface conditions on workpieces, variations in wire feed compositions, and other factors. These variations in weld bead geometry and the resulting diminished weld strength are a significant problem in the automation of welding process.
Although various feedback control systems have previously been used to try to control automated welding processes, such previous feedback control systems have been subject to one or more of several disadvantages. For example, some prior art systems have used sensors directed towards the molten weld pool. Although knowledge about the weld pool is useful, it is not usually sufficient to determine some important variables of the bead which results after hardening of the weld pool. Other prior art arrangements have used infrared or visible radiation detectors for sensing temperature gradients of a newly-laid bead in order to determine the width of the weld bead. Like numerous other processes, this radiation detection process does not detect the bead height or the bead cross sectional area, both of which may be significant bead dimensions in providing for full design weld strength. Additionally, this latter radiation detection method is very sensitive to errors in its calculated bead width because variations in surface conditions may significantly affect apparent temperature gradients.
The application of weld metal, sealant or glue to a workpiece requires one to maintain certain bead dimensions. Variations in weld bead geometry can result from uncertainties in wire feed rate, varying surface conditions on workpiece or variations in feed wire composition. Factors such as variations in sealant or glue supply pressure and nozzle condition can affect the size of the bead which is laid down. If the bead which is laid down in too small, the sealant may not properly seal. On the other had, too large a bead is a waste of sealant or glue and may also hinder the use of the workpiece. Accordingly, too much variation in the size of the bead is quite undesirable.